At present, both the left end and the right end of a vehicular engine are connected with the vehicle body through an engine mounting. The engine mounting consists of a damper assembly, an upper mount bracket and a lower mount bracket. The damper assembly is connected with the engine. A flat lug at an end of the upper mount bracket is connected with a front plate of a front wheel cowling on the vehicle body by bolts, and the lower mount bracket is connected with a stringer of the vehicle body by bolts. Since the engine mounting is generally heavy, during the assembling of the upper mount bracket and the front plate of the front wheel cowling, the engine mounting needs to be supported by an operator with one hand, or else the engine mounting would easily fall off under the condition that the center of gravity of the engine mounting is offset, which would damage the components of the engine mounting or injure the operator. Besides, a pneumatic gun needs to be grasped by the operator with another hand, and a bolt at the head of the pneumatic gun also needs to be stabilized by the operator's hand, which would make it more difficult for a single operator to assemble the engine mounting. Now, the conventional method of assembling the engine mounting by a single operator in a workshop of a vehicle manufacturer is as follows: firstly, the pneumatic gun is put down, the engine mounting is supported by the operator with one hand, and the bolts are preliminarily screwed to the engine mounting by the operator with another hand; then, the bolts are fastened to the engine mounting by the operator with the pneumatic gun. In this way, it needs two steps to assemble the engine mounting to the front plate of the front wheel cowling, which not only increases the labor intensity of the operator but also needs longer assembling time, thus the efficiency is low.